Metal sheet ingots of rectangular cross-section have a number of uses in industry. Such ingots are commonly cast by a process known as “direct chill” casting. This process utilizes an open-topped mold having four fluid-cooled walls, two relatively long side walls and two relatively short end walls. The wide faces of the ingot are formed along the side walls and the short edges of the ingot are formed along the end walls.
The direct chill casting mold has a bottom block which is movable downwardly during the casting operation. Molten metal to be cast is poured into the open top of the mold, and as casting progresses the bottom block is moved downwardly away from the mold.
The molten metal is initially cooled by contact with the fluid-cooled mold walls, causing formation of a solidified outer shell. This is known as “primary cooling”. As the ingot emerges from the bottom of the mold, coolant is sprayed directly onto its outer surface to further cool the ingot. This is known as “secondary cooling”.
Sheet ingots are cast in many sizes, and there is a continuous demand for new ingot sizes having different cross-sectional areas. In order to avoid the need to completely replace a mold for each ingot size, and thereby minimize casting equipment inventory, molds with adjustable walls have been developed. Most commonly, such molds are adjustable in width only, with the short end walls being movable inwardly and outwardly relative to each other. Changing the ingot thickness normally requires replacement of the whole adjustable mold assembly with its corresponding bottom block.
Although numerous types of adjustable molds for direct chill casting have been developed in the past, there remains a need for an effective yet simple and reliable mold system for direct chill casting.